Method and apparatus for transmitting data in very high throughput wireless local area network system

ABSTRACT

A method of transmitting data in a wireless local area network is provided. The method includes the steps of: generating a data unit including a MAC (Medium Access Control) header and MSDU (MAC Service Data Unit), generating an encoded data unit by encoding the data unit, generating one or more spatial blocks by dividing the encoded data unit, dividing each of the one or more spatial block into a first block and a second block, generating a first interleaved block and a second interleaved block by interleaving the first block and the second block respectively, generating a first mapped sequence by mapping the first interleaved block into signal constellation, generating a second mapped sequence by mapping the second interleaved block into signal constellation, generating the transmission signal by performing IDFT (Inverse Discrete Fourier Transform) to the first mapped sequence and the second mapped sequence; and transmitting the transmission signal.

TECHNICAL FIELD

The present invention relates to wireless communications, and moreparticularly, to a method of transmitting data in a wireless local areanetwork (WLAN) system and an apparatus supporting the method.

BACKGROUND ART

With the advancement of information communication technologies, variouswireless communication technologies have recently been developed. Amongthe wireless communication technologies, a wireless local area network(WLAN) is a technology whereby Internet access is possible in a wirelessfashion in homes or businesses or in a region providing a specificservice by using a portable terminal such as a personal digitalassistant (PDA), a laptop computer, a portable multimedia player (PMP),etc.

Ever since the institute of electrical and electronics engineers (IEEE)802, i.e., a standardization organization for WLAN technologies, wasestablished in February 1980, many standardization works have beenconducted.

In the initial WLAN technology, a frequency of 2.4 GHz was usedaccording to the IEEE 802.11 to support a data rate of 1 to 2 Mbps byusing frequency hopping, spread spectrum, infrared communication, etc.Recently, the WLAN technology can support a data rate of up to 54 Mbpsby using orthogonal frequency division multiplex (OFDM). In addition,the IEEE 802.11 is developing or commercializing standards of varioustechnologies such as quality of service (QoS) improvement, access pointprotocol compatibility, security enhancement, radio resourcemeasurement, wireless access in vehicular environments, fast roaming,mesh networks, inter-working with external networks, wireless networkmanagement, etc.

The IEEE 802.11n is a technical standard relatively recently introducedto overcome a limited data rate which has been considered as a drawbackin the WLAN. The IEEE 802.11n is devised to increase network speed andreliability and to extend an operational distance of a wireless network.More specifically, the IEEE 802.11n supports a high throughput (HT),i.e., a data processing rate of up to above 540 Mbps, and is based on amultiple input and multiple output (MIMO) technique which uses multipleantennas in both a transmitter and a receiver to minimize a transmissionerror and to optimize a data rate. In addition, this standard may use acoding scheme which transmits several duplicate copies to increase datareliability and also may use the OFDM to support a higher data rate.

An IEEE 802.11n HT WLAN system employs an HT green field physical layerconvergence procedure (PLCP) protocol data unit (PPDU) format which is aPPDU format designed effectively for an HT station (STA) and which canbe used in a system consisting of only HT STAs supporting IEEE 802.11nin addition to a PPDU format supporting a legacy STA. In addition, anHT-mixed PPDU format which is a PPDU format defined such that a systemin which the legacy STA and the HT STA coexist can support an HT system.

With the widespread use of a wireless local area network (WLAN) and thediversification of applications using the WLAN, there is a recent demandfor a new WLAN system to support a higher throughput than a dataprocessing rate supported by the IEEE 802.11n. A next generation WLANsystem supporting a very high throughput (VHT) is a next version of theIEEE 802.11n WLAN system, and is one of IEEE 802.11 WLAN systems whichhave recently been proposed to support a data processing rate of 1 Gbpsor higher in a medium access control (MAC) service access point (SAP).

In IEEE 802.11 TGac that conducts standardization of a next generationWLAN system, there is an ongoing research on a method of using 88 MIMOand a channel bandwidth of 80 MHz, 160 MHz, or higher to provide athroughput of 1 Gbps or higher and a PLCP format for effectivelysupporting each STA in a WLAN system in which a legacy STA coexists withan HT STA and a VHT STA. There is a need to consider a method capable oftransmitting a PLCP protocol data unit (PPDU) including data bysupporting the use of a wider channel bandwidth of the VHT STA in thelegacy WLAN system, and a wireless apparatus supporting the method.

SUMMARY OF INVENTION Technical Problem

The present invention provides a method in which a wireless local areanetwork (WLAN) system can transmit data by using a wider bandwidth thana frequency bandwidth supported in a legacy WLAN system, and anapparatus supporting the method.

Solution to Problem

In an aspect, a method of transmitting data in a wireless local areanetwork is provided. The method includes the steps of: generating a dataunit including a MAC(Medium Access Control) header and MSDU(MAC ServiceData Unit), generating an encoded data unit by encoding the data unit,generating one or more spatial blocks by dividing the encoded data unit,dividing each of the one or more spatial block into a first block and asecond block, generating a first interleaved block and a secondinterleaved block by interleaving the first block and the second blockrespectively, generating a first mapped sequence by mapping the firstinterleaved block into signal constellation, generating a second mappedsequence by mapping the second interleaved block into signalconstellation, generating the transmission signal by performing IDFT(Inverse Discrete Fourier Transform) to the first mapped sequence andthe second mapped sequence; and transmitting the transmission signal.

The step of generating the transmission signal by performing IDFT mayinclude, if the transmission signal is transmitted in a single frequencyband, generating the transmission signal by performing IDFT by mappingthe first mapped sequence to the upper part of single IDFT and mappingthe second mapped sequence to the lower part of the single IDFT.

The step of generating the transmission signal by performing IDFT mayinclude, if the transmission signal is transmitted in two non-contiguousfrequency bands, generating the transmission signal by performing IDFTby mapping the first mapped sequence and the second mapped sequence toseparate IDFT.

A bandwidth of the single frequency of band may be 160 MHz.

A bandwidth of each of the two non-contiguous frequency bands may be 80MHz.

The data unit may be encoded using BCC (binary convolution code)encoding.

In another aspect, a wireless apparatus is provided. The Apparatusincludes a processor and a transceiver operationally coupled to theprocessor to transmit and receive a transmission signal. The processoris configured for the steps of: generating a data unit including a MAC(Medium Access Control) header and MSDU (MAC Service Data Unit),generating an encoded data unit by encoding the data unit, generatingone or more spatial blocks by dividing the encoded data unit, dividingeach of the one or more spatial block into a first block and a secondblock, generating a first interleaved block and a second interleavedblock by interleaving the first block and the second block respectively,generating a first mapped sequence by mapping the first interleavedblock into signal constellation, generating a second mapped sequence bymapping the second interleaved block into signal constellation,generating the transmission signal by performing IDFT (Inverse DiscreteFourier Transform) to the first mapped sequence and the second mappedsequence and transmitting the transmission signal.

Advantageous Effects of Invention

When transmitting a physical layer convergence procedure (PLCP) protocoldata unit (PPDU), a data field constituting the PPDU is segmented sothat the data field can be transmitted at a specific bandwidth. Thesegmented data field is respectively interleaved and thus can betransmitted through a wider bandwidth by using an interleaver supportingthe existing bandwidth.

A data block in which the data field is segmented can be randomlyallocated to a frequency band, and thus frequency diversity can beobtained. A frequency diversity gain can be more increased by performingsegmentation randomly.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a physical layer architecture of the institute ofelectrical and electronics engineers (IEEE) 802.11.

FIG. 2 is a diagram showing an example of a physical layer convergenceprocedure (PLCP) protocol data unit (PPDU) format used in a wirelesslocal area network (WLAN) system based on the IEEE 802.11n standard.

FIG. 3 shows an example of applying block interleaving to which anembodiment of the present invention can be applied.

FIG. 4 shows an orthogonal mapping matrix based on a channel layer.

FIG. 5 shows frequency tone allocation when supporting a bandwidth of 20MHz and 40 MHz, where the bandwidth is 20 MHz in FIG. 5( a) and 40 MHzin FIG. 5( b).

FIG. 6 shows an example of a PPDU format used in a next generation WLANsystem.

FIG. 7 is a block diagram showing a first example of a method oftransmitting a data field according to an embodiment of the presentinvention.

FIG. 8 is a block diagram showing a second example of a method oftransmitting a data field according to an embodiment of the presentinvention.

FIG. 9 shows a data transmission method according to an embodiment ofthe present invention.

FIG. 10 shows a data transmission method according to another embodimentof the present invention.

FIG. 11 shows a data transmission method according to another embodimentof the present invention.

FIG. 12 shows a process of interleaving a segmented data unit andmapping the data unit to a channel band according to an embodiment ofthe present invention.

FIG. 13 shows a process of segmenting a data unit according to anembodiment of the present invention.

FIG. 14 is a block diagram showing a wireless apparatus according to anembodiment of the present invention.

MODE FOR THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings.

A wireless local area network (WLAN) system according to an embodimentof the present invention includes at least one basic service set (BSS).The BSS is a set of stations (STAs) successfully synchronized tocommunicate with one another. The BSS can be classified into anindependent BSS (IBSS) and an infrastructure BSS.

The BSS includes at least one STA and an access point (AP). The AP is afunctional medium for providing a connection to STAs in the BSS throughrespective wireless media. The AP can also be referred to as otherterminologies such as a centralized controller, a base station (BS), ascheduler, etc.

The STA is any functional medium including a medium access control (MAC)and wireless-medium physical layer (PHY) interface satisfying theinstitute of electrical and electronics engineers (IEEE) 802.11standard. The STA may be an AP or a non-AP STA. Hereinafter, the STArefers to the non-AP STA unless specified otherwise.

The STA can be classified into a very high throughput (VHT)-STA, a highthroughput (HT)-STA, and a legacy (L)-STA. The HT-STA is an STAsupporting IEEE 802.11n. The L-STA is an STA supporting a previousversion of IEEE 802.11n, for example, IEEE 802.11a/b/g. The L-STA isalso referred to as a non-HT STA.

FIG. 1 shows an IEEE 802.11 physical layer (PHY) architecture.

The IEEE 802.11 PHY architecture includes a PHY layer management entity(PLME), a physical layer convergence procedure (PLCP) sub-layer 110, anda physical medium dependent (PMD) sub-layer 100. The PLME provides a PHYmanagement function in cooperation with a MAC layer management entity(MLME). The PLCP sub-layer 110 located between a MAC sub-layer 120 andthe PMD sub-layer 100 delivers to the PMD sub-layer 100 a MAC protocoldata unit (MPDU) received from the MAC sub-layer 120 under theinstruction of the MAC layer, or delivers to the MAC sub-layer 120 aframe received from the PMD sub-layer 100. The PMD sub-layer 100 is alower layer of the PDCP sub-layer and serves to enable transmission andreception of a PHY entity between two STAs through a radio medium. TheMPDU delivered by the MAC sub-layer 120 is referred to as a physicalservice data unit (PSDU) in the PLCP sub-layer 110. Although the MPDU issimilar to the PSDU, when an aggregated MPDU (A-MPDU) in which aplurality of MPDUs are aggregated is delivered, individual MPDUs andPSDUs may be different from each other.

The PLCP sub-layer 110 attaches an additional field includinginformation required by a PHY transceiver to the MPDU in a process ofreceiving the MPDU from the MAC sub-layer 120 and delivering a PSDU tothe PMD sub-layer 100. The additional field attached in this case may bea PLCP preamble, a PLCP header, tail bits required on a data field, etc.The PLCP preamble serves to allow a receiver to prepare asynchronization function and antenna diversity before the PSDU istransmitted. The PLCP header includes a field that contains informationon a PLCP protocol data unit (PDU) to be transmitted, which will bedescribed below in greater detail with reference to FIG. 2.

The PLCP sub-layer 110 generates a PLCP protocol data unit (PPDU) byattaching the aforementioned field to the PSDU and transmits thegenerated PPDU to a reception STA via the PMD sub-layer. The receptionSTA receives the PPDU, acquires information required for data recoveryfrom the PLCP preamble and the PLCP header, and recovers the data.

FIG. 2 is a diagram showing an example of a PPDU format used in a WLANsystem based on the IEEE 802.11n standard.

Referring to FIG. 2, there are three types of PPDUs supported in IEEE802.11n.

FIG. 2( a) shows a legacy PPDU (L-PPDU) format for a PPDU used in theexisting IEEE 802.11a/b/g. Therefore, an L-STA can transmit and receivean L-PPDU having this format in a WLAN system based on the IEEE 802.11nstandard.

An L-PPDU 210 includes an L-STF field 211, an L-LTF field 212, an L-SIGfield 213, and a data field 214.

The L-STF field 211 is used for frame timing acquisition, automatic gaincontrol (AGC) convergence, coarse frequency acquisition, etc.

The L-LTF field 212 is used for frequency offset and channel estimation.

The L-SIG field 213 includes control information for demodulation anddecoding of the data field 214.

The L-PPDU may be transmitted in the order of the L-STF field 211, theL-LTF field 212, the L-SIG field 213, and the data field 214.

FIG. 2( b) is a diagram showing an HT-mixed PPDU format in which anL-STA and an HT-STA can coexist. An HT-mixed PPDU 220 includes an L-STFfield 221, an L-LTF field 222, an L-SIG field 223, an HT-SIG field 224,an HT-STF field 225, a plurality of HT-LTF fields 226, and a data field227.

The L-STF field 221, the L-LTF field 222, and the L-SIG field 223 areidentical to those shown in FIG. 2( a). Therefore, the L-STA caninterpret the data field by using the L-STF field 221, the L-LTF field222, and the L-SIG field 223 even if the HT-mixed PPDU 220 is received.The L-LTF field 222 may further include information for channelestimation to be performed by the HT-STA in order to receive theHT-mixed PPDU 220 and to interpret the L-SIG field 223, the HT-SIG field224, and the HT-STF field 225.

The HT-STA can know that the HT-mixed PPDU 220 is a PPDU dedicated tothe HT-STA by using the HT-SIG field 224 located next to the L-SIG field223, and thus can demodulate and decode the data field 227.

The HT-STF field 225 may be used for frame timing synchronization, AGCconvergence, etc., for the HT-STA.

The HT-LTF field 226 may be used for channel estimation for demodulationof the data field 227. Since the IEEE 802.11n supports single user-MIMO(SU-MIMO), a plurality of the HT-LTF fields 226 may be configured forchannel estimation for each of data fields transmitted through aplurality of spatial streams.

The HT-LTF field 226 may consist of a data HT-LTF used for channelestimation for a spatial stream and an extension HT-LTF additionallyused for full channel sounding. Therefore, the number of the pluralityof HT-LTF fields 226 may be equal to or greater than the number ofspatial streams to be transmitted.

The L-STF field 221, the L-LTF field 222, and the L-SIG field 223 aretransmitted first so that the L-STA also can acquire data by receivingthe HT-mixed PPDU 220. Thereafter, the HT-SIG field 224 is transmittedfor demodulation and decoding of data transmitted for the HT-STA.

Up to fields located before the HT-SIG field 224, transmission isperformed without beamforming so that the L-STA and the HT-STA canacquire data by receiving a corresponding PPDU. In the subsequentlyfields, i.e., the HT-STF field 225, the HT-LTF 226, and the data field227, radio signal transmission is performed by using precoding. In thiscase, the HT-STF field 225 is transmitted so that an STA that receives aprecoded signal can consider a varying part caused by the precoding, andthereafter the plurality of HT-LTF fields 226 and the data field 227 aretransmitted.

Even if an HT-STA that uses 20 MHz in an HT WLAN system uses 52 datasubcarriers per OFDM symbol, an L-STA that also uses 20 MHz uses 48 datasubcarriers per OFDM symbol. Since the HT-SIG field 224 is decoded byusing the L-LTF field 222 in a format of the HT-mixed PPDU 220 tosupport backward compatibility, the HT-SIG field 224 consists of 482data subcarriers. The HT-STF field 225 and the HT-LTF 226 consist of 52data subcarriers per OFDM symbol. As a result, the HT-SIG field 224 issupported using ½ binary phase shift keying (BPSK), each HT-SIG field224 consists of 24 bits, and thus 48 bits are transmitted in total. Thatis, channel estimation for the L-SIG field 223 and the HT-SIG field 224is performed using the L-LTF field 222, and a bit sequence constitutingthe L-LTF field 222 can be expressed by Equation 1 below. The L-LTFfield 222 consists of 48 data subcarriers per one symbol, except for aDC subcarrier.

L_(−26,26)={1,1,−1,−1,1,1,−1,1,−1,1,1,1,1,1,1,−1,−1,1,1,−1,1,−1,1,1,1,1,0,1,−1,−1,1,1,−1,1,−1,1,−1,−1,−1,−1,−1,1,1,−1,−1,1,−1,1,−1,1,1,1,1}  [Equation1]

FIG. 2( c) is a diagram showing a format of an HT-Greenfield PPDU 230that can be used by only an HT-STA. The HT-GF PPDU 230 includes anHT-GF-STF field 231, an HT-LTF1 field 232, an HT-SIG field 233, aplurality of HT-LTF2 fields 234, and a data field 235.

The HT-GF-STF field 231 is used for frame timing acquisition and AGC.

The HT-LTF1 field 232 is used for channel estimation.

The HT-SIG field 233 is used for demodulation and decoding of the datafield 235.

The HT-LTF2 234 is used for channel estimation for demodulation of thedata field 235. Since the HT-STA uses SU-MIMO, channel estimation isrequired for each of data fields transmitted through a plurality ofspatial streams, and thus a plurality of HT-LTF2 fields 234 may beconfigured.

The plurality of HT-LTF2 fields 234 may consist of a plurality of dataHT-LTFs and a plurality of extension HT-LTFs, similarly to the HT-LTF226 of the HT-mixed PPDU 220.

Each of the data fields 214, 227, and 235 respectively shown in FIGS. 2(a), (b), and (c) may include a service field, a scrambled PSDU field, atail bits field, and a padding bits field.

In the HT WLAN system, the HT-SIG field constituting the PPDU can betransmitted in such a manner that a bit sequence constituting the HT-SIGfield is encoded, the encoded HT-SIG field is interleaved, a transmit(Tx) signal is generated by performing modulation and inverse discreteFourier transform (IDFT) that maps a to-be-transmitted signal configuredin a frequency domain to a time domain, a weight of cyclic shiftdiversity (CSD) is applied on an antenna basis, and then the Tx signalis transmitted through a radio frequency (RF) unit by inserting a guardinterval (GI).

In addition, a process of transmitting the data field constituting thePPDU in the HT WLAN system includes scrambling the bit sequenceconstituting the data field, encoding the scrambled bit sequence,parsing the encoded bit sequence to a spatial stream and interleaving adata sequence allocated to each spatial stream, and generating acomplex-valued sequence which is a mapped sequence by performing mappingto a signal constellation map. When binary convolution code (BCC)encoding is used as an encoding scheme in the HT WLAN system, theencoded bit stream is interleaved through a block interleaver. Theinterleaver uses a size of a column NCOL and a row NROW of aninterleaver block according to a defined value. Table 1 below shows thedefined value.

TABLE 1 Parameter 20 MHz 40 MHz N_(COL) 13 18 N_(ROW) 4 × N_(BPSCS)(i_(SS)) 6N_(BPSCS) (i_(SS)) N_(ROT) 11 29

In Table 1, NBPSCS(iSS) denotes the number of bits encoded per onecarrier in each spatial stream (herein, iSS is an integer between 1 andNSS). A method of using such an interleaver includes inputting anencoded bit stream along a row and reading the input bit stream along acolumn. In this case, a method of using block interleaving shown in FIG.3 can be used by reference.

Thereafter, a complex-valued sequence generated for each spatial streamis used to configure a signal for a space-time stream through space-timeblock coding. The signal can be subjected to spatial mapping for eachantenna, and then can be transmitted through an RF unit after performingGI insertion. Herein, the spatial mapping may include a beamformingprocess for MIMO transmission.

Although it is described herein that the HT-SIG field is transmittedthrough one spatial stream, the data field can be transmitted through atleast one or more spatial streams based on MIMO transmission.

As such, the HT-LTF is defined for channel estimation in order to useMIMO in the WLAN system supporting the HT. The HT-LTF is used forchannel estimation similarly to an L-LTF, but has a difference in thatthe HT-LTF can estimate a MIMO channel. In order to estimate the MIMOchannel by using the HT-LTF, an orthogonal mapping matrix PHTLTF is usedby being multiplied by the HT-LTF. The PHTLTF consists of ‘1’ and ‘−1’and can be expressed by Equation 2 below.

$\begin{matrix}{P_{HTLTF} = \begin{bmatrix}1 & {- 1} & 1 & 1 \\1 & 1 & {- 1} & 1 \\1 & 1 & 1 & {- 1} \\{- 1} & 1 & 1 & 1\end{bmatrix}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

Herein, the orthogonal mapping matrix is used in a different sizeaccording to a channel layer, which will be described with reference toFIG. 4.

FIG. 4 shows an orthogonal mapping matrix based on a channel layer.

Referring to FIG. 4, a training symbol is defined on a spatial streambasis, and is transmitted for channel estimation of each spatial stream.When the number of spatial streams is 1, 2, and 4, the number of HT-LTFsto be transmitted is 1, 2, and 4, respectively. When the number ofspatial streams is 3, one extra long training symbol is used so that 4HT-LTFs can be used.

FIG. 5 shows frequency tone allocation when supporting a bandwidth of 20MHz and 40 MHz. The bandwidth is 20 MHz in FIG. 5( a) and 40 MHz in FIG.5( b).

Referring to FIG. 5( a), when supporting 20 MHz bandwidth transmission,a tone #0 is used for a DC. A tone index [−21, −7, 7, 21] is used for apilot, and the remaining tones are used for data transmission.

Referring to FIG. 5( b), when supporting 40 MHz bandwidth transmission,tones #−1, #0, and #1 are used for a DC. A tone index [−53, −25, −11,11, 25, 53] is used for a pilot and is also used for measurement of achannel frequency offset. The remaining tones are used for datatransmission.

Unlike the IEEE 802.11n standard supporting the HT, a next generationWLAN system requires a higher throughput. This is called a very highthroughput (VHT) to distinguish it from the HT. For this, the nextgeneration WLAN system intends to support 80 MHz bandwidth transmission,contiguous 160 MHz bandwidth transmission, non-contiguous 160 MHzbandwidth transmission and/or higher bandwidth transmission. Inaddition, a multi user-multiple input multiple output (MU-MIMO)transmission method is provided for a higher throughput. Hereinafter,this will be described in greater detail by reference to a PPDU formatof a WLAN system supporting the VHT provided in the next generation WLANsystem.

FIG. 6 shows an example of a PPDU format used in a next generation WLANsystem.

Referring to FIG. 6, a PPDU 600 includes an L-STF field 610, an L-LTFfield 620, an L-SIG field 630, a VHT-SIGA field 640, a VHT-STF field650, a VHT-LTF field 660, a VHT-SIGB field 670, and a data field 680.

In a PLCP sub-layer, a MAC protocol data unit (MPDU) including a MACheader and a MAC service data unit (MSDU) is used to generate the datafield 680 by appending a service field, a tail field, and optionally, apadding bit to a PLCP service data unit (PSDU) delivered from a MAClayer. In addition, the PPDU 600 is generated by appending severalfields such as the L-STF field 610, the L-LTF field 620, the L-SIG field630, the VHT-SIGA field 640, the VHT-STF field 650, the VHT-LTF field660, the VHT-SIGB field 670, or the like to the data field 680, anddelivers the PPDU 600 to one or more STAs through a PMD layer.

The L-STF field 610 is used for frame timing acquisition, automatic gaincontrol (AGC), coarse frequency acquisition, etc.

The L-LTF field 620 is used for channel estimation for demodulation ofthe L-SIG field 630 and the VHT-SIGA field 640.

The VHT-SIGA field 640 includes common information required when thePPDU is received by STAs using MU-MIMO transmission. That is, theVHT-SIGA field 640 includes information for interpreting the PPDU 600used in the next generation WLAN. The VHT-SIGA field 640 includesinformation on a spatial stream for each STA, channel bandwidthinformation, STBC, a group identifier, information on an STA to whicheach group identifier is allocated, a short guard interval (GI), andbeamforming information (including information indicating whether a MIMOtransmission type is SU-MIMO or MU-MIMO).

The VHT-STF field 650 is used to improve performance of AGC estimationin MIMO transmission.

The VHT-LTF field 660 is used when the VHT-STA estimates a MIMO channel.

Since the next generation WLAN system supports MU-MIMO, the VHT-LTFfield 660 can be configured by the number of spatial streams in whichthe PPDU 600 is transmitted. In addition, when full channel sounding issupported and performed, the number of VHT-LTF fields 660 may increase.

The VHT-SIGB field 670 includes individual information for each STA. TheVHT-SIGB field 670 includes each STA's coding type and MCS information.A size of the VHT-SIGB field 670 may differ according to the MIMOtransmission type (MU-MIMO or SU-MIMO) and a channel bandwidth used forPPDU transmission.

The next generation WLAN system uses the aforementioned PPDU format andsupports a bandwidth of 80 MHz, contiguous 160 MHz, and/ornon-contiguous 160 MHz (80 MHz+80 MHz). For this, a new coding chain hasto be defined. In particular, when 160 MHz transmission is performed byusing a contiguous frequency band, it needs to be defined differentlyfrom a transmission procedure for a case where 160 MHz transmission isperformed at a non-contiguous frequency band. A data transmission methodfor this will be proposed in the following description. Hereinafter, adata unit includes the concept of a bit sequence constituting the datafield in the PPDU format that can be used in the next generation WLANsystem.

FIG. 7 is a block diagram showing a first example of a method oftransmitting a data field according to an embodiment of the presentinvention. The method of FIG. 7 can be used as an example of a datatransmission method using a contiguous 160 MHz bandwidth in a nextgeneration WLAN system, and also can be used as a data transmissionmethod using a more general bandwidth.

Referring to FIG. 7, the data transmission method according to theembodiment of the present invention encodes a data unit (step S710). Inthis case, the data unit can be encoded by at least one or moreencoders. When a plurality of encoders are used for encoding, an encoderparser can allocate a bit sequence having a specific bit size to eachencoder, and each encoder can perform encoding. An encoding scheme usedin this case may be a binary convolution code (BCC) encoding scheme. Thedata unit input to the encoder parser may be in a state where a bitsequence constituting a data field of a PPDU is scrambled.

The data unit encoded by at least one or more encoders is divided into aplurality of spatial streams by a stream parser (step S720). In thiscase, the encoded data unit divided to respective spatial streams iscalled a spatial block. The number of spatial blocks can be determinedby the number of spatial streams used for PPDU transmission, and can beset to the number of spatial streams.

Each spatial block is divided into at least one or more data segments bya segment parser (step S730). As shown in the example of FIG. 7, thespatial block can be divided into two segments, i.e., a 1st data segmentand a 2nd data segment. If the data unit is generated in accordance with160 MHz transmission according to the embodiment of the presentinvention, the 1st and 2nd data segments divided by the segment parserare divided in accordance with 80 MHz transmission. Therefore, the 1stand 2nd data segments may be interleaved by an interleaver supporting 80MHz data sequences.

The 1st and 2nd data segments are interleaved by respective interleavers(step S740). In this case, the interleavers can perform blockinterleavnig, and more particularly, the interleavers may be BCCencoders for interleaving the 1st data segment and/or the 2nd datasegment to which BCC encoding is applied. The interleaver uses a size ofa column NCOL and a row NROW of an interleaver block according to adefined value. Table 2 below shows the defined value.

TABLE 2 Parameter 20 MHz 40 MHz 80 MHz N_(COL) 13 18 26 N_(ROW) 4 ×N_(BPSCS) 6 × N_(BPSCS) 9 × N_(BPSCS) N_(ROT ()N_(SS) ≦ 4₎ 11 29 58N_(ROT) (N_(SS) > 4)  6 13 28

In Table 2, NBPSCS denotes the number of bits encoded per one carrier ineach spatial stream. A method of using such an interleaver includesinputting an encoded bit stream along a row and reading the input bitstream along a column. The other way around is also possible. Byreference, the aforementioned method of FIG. 3 can be used for the blockinterleaving.

Referring back to FIGS. 7, 1st and 2nd interleaved data segments aremapped based on a constellation map by constellation mappers to generate1st and 2nd mapped data segments (step S750). In this case, the 1st and2nd mapped data segments may have a format of a complex-valued sequence.The 1st and 2nd interleaved data segments may use differentconstellation maps according to a modulation scheme such as BPSK, QPSK,16-QAM, 64-QAM, or 256-QAM.

The 1st and 2nd mapped data segments constitute a signal for aspace-time stream through space-time block coding, and arespatial-mapped for respective antennas (step S760).

The 1st and 2nd mapped data segments are converted by using IDFT (stepS770), and are converted into Tx signals by performing GI insertion(step S780). The converted Tx signals are transmitted through respectiveradio frequency (RF) processes (step S790). In this case, if a bandwidthof a transport channel for PPDU transmission is a contiguous 160 MHzfrequency band, the 1st and 2nd mapped data segments are converted byusing one IDFT, and the 1st mapped data segment can be converted bybeing mapped to an upper part of IDFT and the 2nd mapped data segmentcan be converted by being mapped to a lower part of IDFT.

Although FIG. 7 shows an exemplary data transmission method when a PPDUis transmitted through a transport channel consisting of a contiguousfrequency band, a different transmission method may be used when thePPDU is transmitted through a transport channel consisting of anon-contiguous frequency band. This will be described below withreference to FIG. 8.

FIG. 8 is a block diagram showing a second example of a method oftransmitting a data field according to an embodiment of the presentinvention. The method of FIG. 8 can be used as an example of a datatransmission method using a non-contiguous 160 MHz bandwidth, i.e., 80MHz+80 MHz, in a next generation WLAN system, and also can be used as adata transmission method using a more general bandwidth having anon-contiguous property.

Referring to FIG. 8, the second example of the data transmission methodof the present invention includes encoding a data unit (step S810),generating a spatial block by dividing the encoded data unit withrespect to a spatial stream by a stream parser (step S820), dividing thespatial block into a 1st data segment and a 2nd data segment by asegment parser (step S830), interleaving each of the 1st and 2nd datasegments (step S840), generating 1st and 2nd mapped data segments bymapping the 1st and 2nd interleaved data segments by using aconstellation mapper (step S850), and performing spatial mapping on the1st and 2nd mapped data segments (step S860). Since this is the same assteps S710 to S760 described above with reference to FIG. 7, detaileddescriptions thereof will be omitted.

The 1st and 2nd mapped data segments are converted by using IDFT (stepS870), and are converted into Tx signals by performing GI insertion(step S880). The converted Tx signals are transmitted through respectiveRF processes (step S890). In this case, if a bandwidth of a transportchannel for PPDU transmission is a noncontiguous 160 MHz frequency band,i.e., an 80 MHz+80 MHz frequency band, the 1st and 2nd mapped datasegments are converted by using different IDTFs, and the 1st mapped datasegment can be converted by being mapped to an upper part of IDFT forthe 80 MHz frequency band and the 2nd mapped data segment can beconverted by being mapped to a lower part of IDFT.

Similarly to the data transmission method of FIG. 7 and FIG. 8, anothermethod can be proposed in which a to-be-transmitted data unit istransmitted by being segmented according to a bandwidth of a transportchannel. In this case, the data unit can be segmented in variousmanners. In addition, the segmented data piece may be transmitted bybeing mapped to a frequency band in various manners. This will bedescribed below with reference to the accompanying drawings.Hereinafter, for convenience of explanation, a case of using an 80 MHzbandwidth will be exemplified in an embodiment of the present invention.However, the present embodiment is also applicable not only to the 80MHz bandwidth but also to a case where data is transmitted at 20 MHz, 40MHz, 80 MHz, contiguous 160 MHz, non-contiguous 160 MHz, or much widerbandwidth. For example, the following embodiment is also applicable to acase of performing transmission at contiguous 160 MHz or non-contiguous80 MHz+80 MHz and to a case of using an interleaver supporting 80 MHztransmission.

FIG. 9 shows a data transmission method according to an embodiment ofthe present invention.

Referring to FIG. 9, a MAC layer generates an MPDU by appending a MACheader and an FCS to a MAC service data unit (MSDU) including data to betransmitted, and delivers the generated MPDU to a PHY layer (step S910).The MPDU can be called a PSDU in the PHY layer. The PHY layer generatesa data unit by appending one or more fields including informationrequired for data acquisition to the PSDU delivered from the MAC layer(step S920). Herein, the data unit may be the data field included in thePPDU transmitted by an AP and/or an STA.

The PHY layer segments the data unit (step S930). The segmentationprocess may be the same as the segment parsing process of FIG. 7 andFIG. 8. Since an interleaver supporting a 40 MHz bandwidth is used inthe present embodiment, the data unit is segmented to a size capable of40 MHz transmission. However, when using an interleaver supporting a 20MHz bandwidth, an 80 MHz bandwidth, or a higher bandwidth or aninterleaver supporting other bandwidths, the data unit can be segmentedto fit a corresponding bandwidth size.

The segmented data units are interleaved by respective interleavers(step S940). The interleaving process may be the same as theinterleaving process of FIG. 7 and FIG. 8.

The interleaved segmented data unit is mapped to a channel band (stepS950). In the process of mapping the interleaved segmented data unit toa channel band, each of the interleaved segmented data units may bemapped to a frequency band in a distributed manner. That is, mapping canbe performed such that one segmented data unit is halved so that twodata units can be allocated to non-contiguous channel bands. Byallocating the data units to the non-contiguous channel bands, frequencydiversity can be obtained. After allocating the interleaved segmenteddata unit to the channel band, the data unit is transmitted byperforming IDFT.

In the aforementioned method, an interleaver supporting a 40 MHzbandwidth can be used when transmission is performed by using an 80 MHzbandwidth, and there is no need to newly define an interleaversupporting a wider bandwidth, i.e., 80 MHz bandwidth. Although twointerleavers supporting 40 MHz are defined in the present embodiment,one interleaver supporting 40 MHz can be used by the number of segmenteddata units.

FIG. 10 shows a data transmission method according to another embodimentof the present invention.

Referring to FIG. 10, a MAC layer generates an MPDU by appending a MACheader and an FCS to a MSDU including data to be transmitted, anddelivers the generated MPDU to a PHY layer (step S1010). The MPDU can becalled a PSDU in the PHY layer. The PHY layer generates a data unit byappending one or more fields including information required for dataacquisition to the PSDU delivered from the MAC layer (step S1020).Herein, the data unit may be the data field included in the PPDUtransmitted by an AP and/or an STA.

The PHY layer encodes a bit sequence constituting the received data unitbefore segmenting the data unit (step S1030).

The PHY layer segments the encoded data unit (step S1040). Since aninterleaver supporting a 40 MHz bandwidth is used similarly to thesegmentation process of FIG. 9, the encoded data unit may be segmentedto a size capable of 40 MHz transmission. However, when using aninterleaver supporting a 20 MHz bandwidth, an 80 MHz bandwidth, or ahigher bandwidth or an interleaver supporting other bandwidths, the dataunit can be segmented to fit a corresponding bandwidth size.

The segmented data units are interleaved by respective interleavers(step S1050). The interleaving process may be the same as theinterleaving process of FIG. 7 and FIG. 8.

The interleaved segmented data unit is mapped to a channel band (stepS1060). Herein, an interleaved segmented data unit 1 and an interleavedsegmented data unit 2 can be allocated to a frequency band by beingdivided to a size of 20 MHz, and may be allocated to a channel bandother than contiguous channel bands. That is, as illustrated, segmenteddata units 1 a and 1 b of the segmented data unit 1 and segmented dataunits 21 and 2 b of the segmented data unit 2 may be mapped in a crossedmanner. However, the segmented data units 1 a, 1 b, 2 a, and 2 b may bemapped to the frequency band by being divided according to any bandwidthsize instead of being divided to the size of 20 MHz. Thereafter, themapped segmented data units may be transmitted after performing IDFT.

FIG. 11 shows a data transmission method according to another embodimentof the present invention.

Referring to FIG. 11, a MAC layer generates an MPDU by appending a MACheader and an FCS to a MSDU including data to be transmitted, anddelivers the generated MPDU to a PHY layer (step S1110). The MPDU can becalled a PSDU in the PHY layer. The PHY layer generates a data unit byappending one or more fields including information required for dataacquisition to the PSDU delivered from the MAC layer (step S1120).Herein, the data unit may be the data field included in the PPDUtransmitted by an AP and/or an STA. The PPDU is generated by appending aPLCP header and a preamble including a training symbol (step S1120).

The PHY layer segments the data unit (step 1130). Since an interleaversupporting a 40 MHz bandwidth is used similarly to the segmentationprocess of FIG. 9, the encoded data unit may be segmented to a sizecapable of 40 MHz transmission. However, when using an interleaversupporting a 20 MHz bandwidth, an 80 MHz bandwidth, or a higherbandwidth or an interleaver supporting other bandwidths, the data unitcan be segmented to fit a corresponding bandwidth size.

The PHY layer encodes a bit sequence constituting a segmented data unit1 and a segmented data unit 2 which are generated by segmenting the dataunit. In this case, encoding can be performed by individual encoders forthe segmented data units (step S1140).

The encoded segmented data units are interleaved by respectiveinterleavers (step S1150). The interleaving process may be the same asthe interleaving process of FIG. 7 and FIG. 8.

The interleaved segmented data unit is mapped to a channel band (stepS1160). Herein, an interleaved segmented data unit 1 and an interleavedsegmented data unit 2 can be allocated to a frequency band by beingdivided to a size of 20 MHz, and may be allocated to a channel bandother than contiguous channel bands. Since this is similar to themapping process (step S1060) of FIG. 10, detailed descriptions thereofwill be omitted. The segmented data units mapped to the channel band maybe transmitted after performing IDFT.

Although it is shown in FIG. 10 and FIG. 11 that the segmented data unitis interleaved and is then mapped to the channel band, the presentinvention is not limited thereto. This will be described in greaterdetail with reference to FIG. 12.

FIG. 12 shows a process of interleaving a segmented data unit andmapping the data unit to a channel band according to an embodiment ofthe present invention.

Referring to FIG. 12, segmented data units are encoded individually(step S1210). Although it is shown herein that the encoding process isperformed after segmentation, the encoding process may be performedbefore the segmenting of the data unit

The encoded segmented data units are interleaved by individualinterleavers (step S1220). The interleaving process may be performedsimilarly to the interleaving process of FIG. 7 and FIG. 8. However, inorder to rearrange an order of listing a bit sequence constitutingencoded segmented data units 1 and 2, the interleaver may be configuredto be able to implement another interleaving method.

The interleaved segmented data unit is mapped to a channel band (stepS1230). Herein, instead of mapping the segmented data units 1 and 2 byre-dividing the data units according to a specific bandwidth size,mapping is performed in such a manner that output bits of theinterleaver are allocated one by one to subcarriers.

In doing so, without having to newly define an interleaver supporting an80 MHz bandwidth, the same effect as performing interleaving accordingto one 80 MHz bandwidth can be achieved by using the existinginterleaver. In addition, a bit constituting the conventional data unitcan be mapped to a channel band more randomly than a result of channelband mapping proposed in the aforementioned embodiment. The interleavingand channel mapping process proposed in FIG. 12 is applicable to theaforementioned data transmission method.

In the aforementioned various embodiments, a process of segmenting adata unit into a segmented data unit may be implemented by a method ofrearranging an order of a bit sequence constituting the data unit anddividing it into a segmented data unit 1 and a segmented data unit 2. Inthis method, the data unit is interleaved more randomly, and thus Txdiversity can be increased.

This will be described in detail with reference to FIG. 13. FIG. 13shows a process of segmenting a data unit according to an embodiment ofthe present invention.

Referring to FIG. 13, the data unit is segmented to a size capable of 40MHz transmission (step S1310). In this case, a bit sequence constitutingthe data unit is allocated to a segmented data unit 1 and a segmenteddata unit 2 in sequence. Herein, a unit of allocating the bit sequenceto each segmented data unit may be a modulation order or a bit unit.

Each segmented data unit is delivered to an interleaver and is theninterleaved (step S1320). The interleaving process can be performedsimilarly to the interleaving process of FIG. 7 and FIG. 8. Each of theinterleaved segmented data units may be allocated to a channel band, andmay be transmitted after IDFT.

When the bit sequence of the data unit is segmented by being allocatedorderly, complexity is higher than a method of segmenting a full bitsequence by dividing the sequence in forward/backward order according toa bandwidth size. However, there is an advantage in that an interleavingresult of the data unit can be obtained more randomly. In addition, afrequency diversity gain can be obtained more.

The data unit segmentation process of FIG. 13 can be applied to thesegmentation process of the aforementioned embodiment described withreference to the drawings.

FIG. 14 is a block diagram showing a wireless apparatus according to anembodiment of the present invention. A radio apparatus 1400 may be an APor an STA.

Referring to FIG. 14, the wireless apparatus 1400 includes a processor1410, a memory 1420, and a transceiver 1430. The transceiver 1430transmits and/or receives a radio signal, and implements a PHY layer ofIEEE 802.11. The processor 1410 is functionally coupled to thetransceiver 1430, and implements a MAC layer of IEEE 802.11 and a PHYlayer for performing a method of transmitting a PPDU delivered from theMAC layer. The processor 1410 is configured to implement the embodimentof the present invention shown in FIG. 6 to FIG. 13 related to a datatransmission method in WLAN.

The processor 1410 and/or the transceiver 1430 may include anapplication-specific integrated circuit (ASIC), a separate chipset, alogic circuit, and/or a data processing unit. The memory 1420 mayinclude a read-only memory (ROM), a random access memory (RAM), a flashmemory, a memory card, a storage medium, and/or other equivalent storagedevices. When the embodiment of the present invention is implemented insoftware, the aforementioned methods can be implemented with a module(i.e., process, function, etc.) for performing the aforementionedfunctions. The module may be stored in the memory 1420 and may beperformed by the processor 1410. The memory 1420 may be located insideor outside the processor 1410, and may be coupled to the processor 1410by using various well-known means.

The aforementioned embodiments include various exemplary aspects.Although all possible combinations for representing the various aspectscannot be described, it will be understood by those skilled in the artthat other combinations are also possible. Therefore, all replacements,modifications and changes should fall within the spirit and scope of theclaims of the present invention.

1.-7. (canceled)
 8. A method of transmitting data by a transmitter in awireless local area network, the method comprising the steps of:generating an encoded data unit by encoding transmission data;generating one or more spatial blocks by re-arranging the encoded dataunit; determining a transmission bandwidth to be equal to or less than160 MHZ; if the transmission bandwidth is equal to 160 MHZ, dividing theone or more spatial blocks into a first frequency segment and a secondfrequency segment; interleaving the first segment and the second segmentrespectively to generate a first interleaved segment and a secondinterleaved segment; generating a first and second mapped sequence byrespectively mapping the first and second interleaved segments into asignal constellation; performing a first and second Inverse DiscreteFourier Transform (IDFT) on the first and second mapped segments,respectively, to generate a first and second transmission signal; andtransmitting the first and second transmission signals.
 9. The method ofclaim 8, wherein, if the transmission bandwidth is less than 160 MHZ,the method further comprises: interleaving the one or more spatialblocks to generate one or more interleaved blocks; generating one ormore mapped sequences by mapping the one or more interleaved blocks intoa signal constellation; generating and transmitting another transmissionsignal without performing the Inverse Discrete Fourier Transform (IDFT)on the first and second mapped sequence; and transmitting the othertransmission signal.
 10. The method of claim 8, wherein the step ofdividing the one or more spatial blocks into a first frequency segmentand a second frequency segment comprises: dividing the first and secondfrequency segment into respective first and second segment blocks; andmapping bits of each of the first and second blocks into correspondingfrequency subblocks.
 11. The method of claim 8, wherein the step ofperforming the first and second Inverse Discrete Fourier Transform(IDFT) on the first and second mapped segments, respectively, comprises:performing two first IDFTs on the first mapped segment; and performingtwo second IDFTs on the second mapped segment.
 12. The method of claim8, wherein the step of interleaving the first segment and the secondsegment respectively to generate the first interleaved segment and thesecond interleaved segment comprises: interleaving the first and secondsegment with a first and second 80 MHz interleaver, respectively. 13.The method of claim 12, wherein the first and second 80 MHz interleaverscomprise: first and second binary convolutional coding (BCC)interleavers, respectively.
 14. The method of claim 8, wherein the stepof determining the transmission bandwidth comprises: determining if thetransmission bandwidth is one of a contiguous 160 MHz bandwidth and a80+80 non-contiguous bandwidth.
 15. The method of claim 8, wherein abandwidth of each of the two frequency segments is 80 MHz.
 16. A devicein a wireless local area network, comprising: a transmitter; and acontroller operatively connected to the transmitter and configured togenerate an encoded data unit by encoding transmission data; generateone or more spatial blocks by re-arranging the encoded data unit,determine a transmission bandwidth to be equal to or less than 160 MHZ,if the transmission bandwidth is equal to 160 MHZ, divide the one ormore spatial blocks into a first frequency segment and a secondfrequency segment, interleave the first segment and the second segmentrespectively to generate a first interleaved segment and a secondinterleaved segment, generate a first and second mapped sequence byrespectively mapping the first and second interleaved segments into asignal constellation, perform a first and second Inverse DiscreteFourier Transform (IDFT) on the first and second mapped segments,respectively, to generate a first and second transmission signal, andtransmit the first and second transmission signals.
 17. The device ofclaim 16, wherein, if the transmission bandwidth is less than 160 MHZ,the controller is configured to: interleave the one or more spatialblocks to generate one or more interleaved blocks, generate one or moremapped sequences by mapping the one or more interleaved blocks into asignal constellation, generate another transmission signal withoutperforming the Inverse Discrete Fourier Transform (IDFT) on the firstand second mapped sequence, and transmit the other transmission signal.18. The device of claim 16, wherein controller is configured to: dividethe first and second frequency segment into respective first and secondsegment blocks, and map bits of each of the first and second blocks intocorresponding frequency subblocks.
 19. The device of claim 16, whereincontroller is configured to: perform two first IDFTs on the first mappedsegment, and perform two second IDFTs on the second mapped segment. 20.The device of claim 16, wherein controller is configured to: interleavethe first and second segment with a first and second 80 MHz interleaver,respectively.
 21. The device of claim 20, wherein the first and second80 MHz interleavers comprise: first and second binary convolutionalcoding (BCC) interleavers, respectively.
 22. The device of claim 16,wherein the controller is configured to determine if the transmissionbandwidth is one of a contiguous 160 MHz bandwidth and a 80+80non-contiguous bandwidth.
 23. The device of claim 16, wherein abandwidth of each of the two frequency segments is 80 MHz.